Abstract Responses to soil compaction and flooding by 12 Salix species were studied in small mesocosms in a greenhouse over a period of 8 weeks. Two independent experiments were conducted: response of rooted cuttings to soil compaction and response of the same species to three weeks of flooding. Soil atmosphere was analyzed in all treatments. Regardless of level of compaction, oxygen levels were stable and close to atmospheric proportions. However, concentration of carbon dioxide gradually increased in compacted treatments and was the highest in the most compacted soil. Concentration of ethylene remained more or less stable in the compaction treatments. In the flooding treatments a significant decrease of oxygen concentration (9.1%), and significant increases of carbon dioxide (2.15%) and ethylene (1.57μl/liter) took place. All species except S. amygdaloides produced equal or higher biomass in compacted soil compared to a control. Flooding had little effect on the growth of above or below ground parts for most species. Anaerobic conditions triggered a wide range of morphological adaptations: lenticel hypertrophy, formation of adventitious roots (including roots with enhanced aerenchyma), roots growing along the water surface, and roots exhibiting negative gravitropism. Our principal finding was that neither soil compaction nor flooding caused significant reduction in growth of willows.